Existing commercial dishwashing compositions are usually tablets formed by compression and consolidation of particulates. Such tablets are usually individually wrapped, in order to keep them in good condition. However it is an inconvenience for consumers, to have to unwrap a tablet for each wash.
Important components of a dishwasher detergent composition are builders, bleach, bleach activators, enzymes, and surfactants (not all of which may be present in a given composition). Builders are most commonly phosphates, for example sodium tripolyphosphate (STPP). Phosphates are extremely effective builders in dishwashing compositions acting as a chelating agents to combat or capture metal ions in solution. Not only can they bind calcium and magnesium ions, they can also act as an alkalinity source for the wash liquor, and are user to buffer the wash liquor about pH 9, together with other chemicals present. Also, they are able to keep existing calcium carbonate in the wash liquor in a dispersed form, to prevent spotting onto tableware. Phosphates also support the bleaching efficiency of the bleach system, if one is present.
As bleaches, generally hypochlorides i.e. sodium dichloroisocyanurate or oxygen based bleaches, for example perborates, percarbonates, persulfates or other peroxide derivatives together with bleach activators e.g. TAED are used. They assist in the removal of bleachable stains from the dishware. Amylases and proteases are efficient enzymes to remove starch and protein soils. Surfactants can emulsify fatty soils.
In the present invention we are seeking to supply detergent compositions in delivery cartridges containing a plurality of unit dose elements of the composition. The composition would probably be retained in a series of separate chambers and some of the unit dose elements will be present in the dishwasher for several cycles. The above described detergent formulations, the current standards, would not to be suitable to survive the harsh conditions (up to 75° C. and 100% humidity) in the dishwasher over several cycles. One reason for this is temperature and humidity sensitivity of the bleach components and the enzymes in the described formulas. Perborates and percarbonates undergo decomposition under these conditions. Enzymes are known to be adversely affected by the effect of heat and/or humidity especially when subjected to these conditions for prolonged periods of time. This is further exacerbated by the presence of bleach components. In addition, existing detergent formats such as powders or tablets offer, due to their micro-porous structure, a high surface area to the dishwasher environment which accelerates decomposition. They readily absorb water and consequently can lose their structure, and their shape.
JP002000063894AA discloses detergent compositions comprising 2-75 wt % sodium glutamic acid diacetate. The compositions are said to be safe to handle.
It has already been disclosed to provide in an automatic dishwasher devices to receive/hold a plurality of detergent unit doses; see for example US2005/0139241 and US2002/0117511.
An aim of the present invention is to find a stable composition and/or product format without compromising on cleaning performance and other performance indicators like spotting and filming. In particular, it is an aim of the present invention to find such a composition or format which exhibits acceptable stability when subjected to two or more cycles of an automatic dishwasher.